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Poster: Jonathan Aizen Date: Nov 7, 2002 2:03am
Forum: etree Subject: Re: Re: FLAC checksums - A note to uploaders

Okay, so what I've gathered is that:

1) FLAC stores checksum info in the FLAC files themselves (cool... I do wonder what happens when a file gets corrupted though).
2) FFP (FLAC Fingerprint) files are sort of comparable to MD5 files, yet they are not actually necessary or used to verify files. They serve as a means of comparing two copies of a show.

What this essentially means is that it would be truly fantastic if people could generate FFP files for any FLAC shows uploaded. I will modify the import process so that it compares the contents of such a file with the db.etree.org database as well as store these contents in the database.

Thanks for the link!

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Poster: Diana Hamilton Date: Nov 7, 2002 3:50am
Forum: etree Subject: Re: FLAC ffp.txt- A note to uploaders

Thanks to wiki magic, the convenience to archive.org is now listed as a good reason to make fingerprint files, see
FlacFingerprint and
FlacFaq

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Poster: ssamadhi97 Date: Nov 7, 2002 5:58am
Forum: etree Subject: Re: FLAC ffp.txt- A note to uploaders

a FLAC fingerprint is an md5 hash of the actual audio data in the flac file, in raw headerless Intel (little-endian) PCM format.

it is stored internally in flac files, the ffp file is generated from those stored values, to make checking and comparing of remote flac files more convenient (you don't have to dl the whole file to extract the fingerprint)

additionally this means that the fingerprint can be directly generated from wav files as well (tech note: by generating a file of the data block only). it is not difficult either to extract the fingerprint from monkey's audio or shorten files. if there's the need for a tool to do this (to compare flac filesets with shn or ape filesets and to improve the cross-format friendliness of the community ;) ), i can work on that..



this is why i'm really wondering which ******* did decide to call it a _flac_ fingerprint (of all formats), even though it's just a md5 hash of the UNCOMPRESSED music

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Poster: ssamadhi97 Date: Nov 7, 2002 6:09am
Forum: etree Subject: Re: FLAC ffp.txt- A note to uploaders

oh yeah, to detect corruption of the flac files themselves.. just let flac test 'em, it'll report any errors.

or you _can_ generate md5 files, even though etree seems to be against it to avoid confusion. (well, either you educate people properly or you just say "don't!!" :P)

actually you can generate an md5 hash of just about everything, but it's more useful for formats which are inherently difficult to verify, for example mpeg videos. (as opposed to most modern lossless audio file formats, which all support verification / internal error detection)